Study links smallpox exit to HIV spread

by Thomas H. Maugh II - May. 19, 2010 12:00 AMLos Angeles Times

The worldwide eradication of smallpox in the mid-20th century was a public-health achievement, but it may have set the stage for the HIV pandemic of the latter half of the century, researchers reported Tuesday.

Laboratory tests suggest that immunity to smallpox triggered by the vaccinia (smallpox) vaccine can inhibit replication of the AIDS virus. Such vaccination could have kept HIV transmission partially under control in the early days of the outbreak, but withdrawal of the smallpox vaccine in the 1950s would have freed it to spread, researchers said.

Dr. Raymond S. Weinstein of the biodefense program at George Mason University in Manassas, Va., and his colleagues recruited 20 Navy personnel. Half had received normal vaccinations and half had received both those vaccinations and, within the previous three to six months, vaccination against smallpox. The researchers extracted white blood cells from all the subjects and exposed them to HIV in a culture dish. They reported in the journal BMC Immunology that HIV replication was slowed by about 80 percent in the cells from those who had received smallpox vaccination.